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One of the gill-like breathing organs of certain aquatic insect larvæ. They contain tracheal tubes somewhat similar to those of other insects.

are eel-like in form, and have no teeth except a small patch on the palate. The external gills are persistent through life.

ternal cavities of animals belonging to all classes. Many species are found, also, on the gills and skin of fishes. A few species are parasitic on man, and some, of which the fluke is the most important, are injurious parasites of domestic animals. The trematodes usually have a flattened body covered with a chitinous s…

The gill of a crustacean in which the branchial filaments are slender and cylindrical, as in the crawfishes.

nterior ones. They usually have broad, thin, and disklike bodies, and are parasite on the gills and skin of fishes.

hich construct, and habitually live in, tubes. The head or anterior segments usually bear gills and cirri. Called also Sedentaria, and Capitibranchiata. See Serpula, and Sabella.

ilated in the form of a sac, pierced by several series of ciliated slits, and serves as a gill.

Having but one gill, as certain molluscs.

of which, as O. marulius, become over four feet long. They have a special cavity over the gills lined with a membrane adapted to retain moisture to aid in respiration, and are thus able to travel considerable distances over the land at night, whence the name. They construct a curious nest for their young. Called also l…

Any arthropod that breathes by means of gills.

s, etc. (b) (Zoöl.) Any one of several species of marine bivalve shells of the genus Aspergillum, or Brechites. The valves are small, and consolidated with the capacious calcareous tube which incases the entire animal. The tube is closed at the anterior end by a convex disk perforated by numerous pores, or tubules, and…

A division of marine gastropods in which the gills are developed on both sides of the body and the renal organs are also paired. The abalone (Haliotis) and the keyhole limpet (Fissurella) are examples.